The present invention is directed to a system for simultaneously using a video signal to send data to a computer and to display a video picture. In particular, the data sent to the computer may be used to control the computer.
Along with the expanding market for new computer software programs, has emerged the use of broadcast and closed circuit television to either demonstrate or teach the use of such new programs on computers. This can be especially valuable for software programs which may be used by personal computers commonly found in the homes of consumers. In filming such a program it is very difficult to obtain a clear picture of the video screen from a computer monitor being used to demonstrate the computer program. It is an object of the present invention to permit a television program to be broadcast simultaneously with software or computer control data which can be transmitted to and received by a computer attached to a television being viewed.
There are a number of systems which have been developed to send computer data by way of a video signal. In U.S. Pat. No. 3,984,624, Waggener discloses a video system in which a single digital bit is combined with a horizontal scan line of an analog video signal. The bit is added at a predetermined location on a scan line and those predetermined locations are varied in order to prevent visible deterioration of the video picture. In Waggener, the digital bit is superimposed on the analog signal.
In U.S. Pat. No. 4,413,281, Thonnart discloses a method for sending teletext simultaneously with an analog television signal. In U.S. Pat. No. 4,368,486, Degoulet, et al. disclose a system for superimposing a marking code on televised video pictures. Detection of this code may be required so that programs are only displayed at receivers that have requested or paid for the program. In U.S. Pat. No. 3,691,295, Fisk discloses a system in which digital data can be sent from the end of a cable having a television display device back through the cable to the other end of the cable from which the video source has been provided. The digital data can be taken off of the video signal on the coax cable and received at the video source. The digital data supplied by Fisk is superimposed on the video's signal.
In U.S. Pat. No. 4,530,048, Proper discloses a controller which can be used to employ a video cassette recorder as a digital storage device.